Disclaimer: I'm an old man going senile, so the following might not be accurate.
A device or softphone uses a XMPP priority level when it logs onto GV. The highest level is 127. If multiple devices are logged on to GV, the one with the highest priority will receive the incoming calls.
If 2 devices have the same priority I don't know if the first or last to sign on that will get the incoming calls.
See XMPP priority here:
https://simonics.com/blog/I believe the OBi uses priority 127, so if GrooveIP doesn't use priority 127 you're SOL.
Try powering off your OBi, then logon with GrooveIP and then power on the OBi.
If that fails, instead of using GrooveIP try Bill Simons GV Gateway with a SIP softphone.
He uses priority 127 in his gateway.
The fix would be if Obihai would have the XMPP priority level as a config option.